With conventional refrigerant systems, known as chillers, an evaporator provides a cooling effect that can be used wherever needed, and a main condenser releases waste heat to atmosphere. In cases where there is a use for the waste heat, such as, for example, to heat domestic water or to heat some other external process, a chiller may be provided with a second condenser or heat-recovery condenser. Instead of the main condenser releasing heat to the atmosphere, heat from the heat-recovery condenser can be used for driving the external process. Depending on the need for heat, the chiller might switch between which of its two condensers it activates, or perhaps the two condensers might operate simultaneously to share the condensing function.
When activating a heat-recovery condenser while deactivating the main one, it can be difficult avoiding adverse refrigerant flow between the two. Some gaseous refrigerant from an inactive main condenser, for instance, might flow counter to that of liquid refrigerant leaving the heat-recovery condenser. Such counter flow of fluids can reduce the system's overall effectiveness.
In some cases, the flow pattern of gaseous refrigerant flowing from an inactive main condenser to an active heat-recovery condenser can produce a pressure drop sufficient to create an excessively high pressure differential between the two condensers. An excessive pressure differential can force liquid refrigerant to back up into the shell of the heat-recovery condenser, which reduces the chiller's performance in the a heat-recovery mode.
Due to the drawbacks of current heat-recovery chiller systems, there is a need for a refrigerant system that can recover waste heat more effectively without adverse system effects.